The machine tool is a power machinery manufacturing unit mainly used for cutting metal or used in relevant manufacturing and processing of metal parts. In terms of the field of application, the machine tool can be divided into different types, such as formation, cutting and connection. To put it in greater details, the machine tools comprise lathes, milling machines, grinders, drill. Since the machine tool is mainly used for processing metals, the mechanical design of the machine tool is mainly for processing an object (also referred as a workpiece) by using a processing tool (also referred as a cutting tool) by generating relative movement between the processing tool and the workpiece. For example, the cutting tool can perform a reciprocating movement in the direction along the central axis of the workpiece. The reciprocating movement comprises a forward stroke and a return stroke. The processing operation disclosed above can be performed in the forward stroke, but the cutting tool and the workpiece are separated from each other in the return stroke.
With the continual advance and improvement in the automated production technology, the design of the machine tool is also directed towards automatic control and computer control, such that the manufacturing and processing operation with high precision can be achieved. However, the operation of ordinary machine tool still has many errors such as poor precision of the parts and poor transmission of the mechanical force. The performance of the processing operation will be affected if these errors are not corrected through the adjustment and compensation of parameters.
Referring to FIG. 1, a structural diagram of partial components of a machine tool 10 is shown. As indicated in FIG. 1, the machine tool 10 comprises a platform 11, a lead screw 12, a decoder 121, a servo driver 122 and a nut seat 13. The nut seat 13 is mounted on the lead screw 12 and together forms a ball screw. That is, the lead screw 12 can be controlled through the movement of the decoder 121 and driven by the servo driver 122 to generate rotation which further drives the nut seat 13 to be displaced towards a first direction D1 or a second direction D2.
In respect of the processing process, the first direction D1 can be a return stroke and the second direction D2 can be a forward stroke, that is, the two directions are opposite to each other. Next, a bearing groove 131 of the nut seat 13 has a gap B1, and a bearing column 111 of the platform 11 is movably disposed inside the bearing groove 131. That is, the bearing column 111, movable inside the bearing groove 131, can contact the bearing groove 131 to be driven by the bearing groove 131, such that the platform 11 disposed on the bearing column 111 can be moved in response to the displacement of the nut seat 13 disposed under the bearing groove 131.
As disclosed above, the gap B1 of the bearing groove 131 is a backlash. As indicated in FIG. 1, the bearing column 111 is located at the center of the bearing groove 131, and the distance from the bearing column 111 to one side of the bearing groove 131 can be regarded as a backlash error. An actual statistical result shows that as the movement speed increases, the backlash error will decrease and approach to a fixed value; as the movement speed decreases, the backlash error will increase.
To put it in greater details, due to the relative sliding between the platform 11 and the nut seat 13, the platform 11 (comprises the bearing column 111) will generate friction of motion, the lead screw 12 will generate flexible balance of transmission, and the bearing column 111 will cause abrasion on the bearing groove 131 in the long term. These factors will eventually change the gap B1. Moreover, during the processing operation, if accurate information of the gap B1 is lacking, relevant calculation of compensation will be biased. Therefore, periodical detection and correction of the positioning precision of the mechanism has become a necessary procedure of maintenance to avoid the processing error of the platform 11.
High production efficiency is demanded in the industry of precision machinery manufacturing. Therefore, how to detect the backlash error within a shortest time to increase positioning precision has always been a prominent task for the industry. Currently, the backlash error of the machine tool is normally detected by using a detector such as a laser interferometer. Such detection method not only increases equipment cost but also incur a large amount of time and labor in the installation, testing and uninstallation during the detection operation.
Therefore, how to effectively, correctly and automatically detect the backlash error without increasing manufacturing cost and wasting time and labor has become an important direction of development for the present disclosure.